Snap closure.
Lightweight fabric.
This is vintage so please see measurements below.

Measurements:
Neck opening 19”
From the neck (on the side) to the shoulder seam 2”
Around the arm opening 20”
Across the back (armpit seam to armpit seam) 14”
Length (from the center-top back neck seam/nape to the bottom edge) 25”
Around the bottom 22”